Modified Z-source inverter based three phase induction motor drive for solar PV applications

Various converter topologies have been developed from many years for the effective operation of solar photovoltaic (SPV) systems. Induction motor application using SPV source requires an efficient converter which can produce higher value of AC voltage output from the PV input and also implement v/f control with reduced losses and wide range of speed control. Here a modified Z-source inverter for V/f control of induction motor driven from a Solar PV system is presented. Using Z source network, voltage levels higher than the input value can be obtained without requiring a boost converter. This can be utilized in SPV applications for obtaining required DC voltage for the inverter. An improved PWM inverter with HERIC topology combined with Z source network is presented for the induction motor application. The new topology is found to have better performance with reduced switching losses compared to the conventional inverters. The topology is evaluated for variable speed applications and it is found to give satisfactory results compared to conventional v/f control especially for low speeds.